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<h2 id="Oracle的服务（需要开启的服务）"><a href="#Oracle的服务（需要开启的服务）" class="headerlink" title="Oracle的服务（需要开启的服务）"></a>Oracle的服务（需要开启的服务）</h2><ul>
<li>OrcaleServiceorcl:orcale启动服务</li>
<li>OracleOraDb11g_home1TNSListener:oracle监听器服务</li>
<li>OracleDBConsoleorcl:控制台服务<span id="more"></span>

</li>
</ul>
<h2 id="Oracle账户"><a href="#Oracle账户" class="headerlink" title="Oracle账户"></a>Oracle账户</h2><ul>
<li>sys：   超级管理员（Oracle 工程师）</li>
<li>system：管理员（Oracle 管理人员）</li>
<li>scott： 普通用户 （普通人员）默认密码：tiger</li>
</ul>
<ul>
<li><strong>Oracle 11gxe版本不自带scott账号，需要自行创建</strong></li>
</ul>
<h2 id="Oracle创建用户"><a href="#Oracle创建用户" class="headerlink" title="Oracle创建用户"></a>Oracle创建用户</h2><ul>
<li><strong>创建用户</strong></li>
<li><code>create user  用户名 identified by 密码</code></li>
<li><strong>赋予数据库登录连接权限</strong></li>
<li><code>grant connect to  用户名;</code></li>
<li><strong>赋予资源操纵权限</strong></li>
<li><code>grant resource to 用户名;</code></li>
</ul>
<h2 id="Oracle修改密码"><a href="#Oracle修改密码" class="headerlink" title="Oracle修改密码"></a>Oracle修改密码</h2><ul>
<li><p>第一种方法</p>
<ol>
<li>在cmd命令行中使用命令：<code>sqlplus / as sysdba</code></li>
<li>然后使用命令：<code>alter user 用户名 identified by 新密码;</code></li>
</ol>
</li>
<li><p>第二种方法</p>
<ol>
<li>在cmd命令行中使用命令：<code>sqlplus /nolog</code></li>
<li>然后使用命令：<code>conn as sysdba</code></li>
<li>然后输入一个已知的用户名和密码</li>
<li>然后使用命令：<code>alter user 用户名 identified by 新密码;</code></li>
</ol>
</li>
</ul>
<h2 id="单表查询-select"><a href="#单表查询-select" class="headerlink" title="单表查询-select"></a>单表查询-select</h2><ul>
<li><p>知识点</p>
<ul>
<li>select * from 表名  查询表中所有的数据</li>
<li>select 字段名1，字段名2，..from 表名 查询指定字段的所有值，不同字段之间使用逗号。隔开使用算术表达式：select 字段名(运算符），字段名(运算符）…from 表名</li>
</ul>
</li>
<li><p>案例</p>
<ul>
<li><p><code>select * from emp</code>—查询所有员工信息<br> <strong><code>select ename,job,sal from emp</code>–查询员工姓名，工作，薪资</strong></p>
</li>
<li><p>查询所有员工一年的工资，以及每位员工年终3000后的所有薪资（不包括津贴）<br><strong><code>select ename,job,sal*12,sal*12+3000 from emp</code>  使用运算符</strong>    </p>
</li>
</ul>
</li>
</ul>
<h2 id="别名操作-as"><a href="#别名操作-as" class="headerlink" title="别名操作-as"></a>别名操作-as</h2><ul>
<li>使用操作<ul>
<li>as可以省略不写，如果有特殊字符获取空格使用双引号添加别名</li>
</ul>
</li>
<li>实例<ul>
<li><code>select ename 姓名,job 工作,sal * 12 年资,sal * 12+3000 年薪 from emp</code>          <strong>直接在字段后面添加别名</strong></li>
<li><code>select ename &quot;姓名&quot;,job 工作,sal * 12 ’年资’,sal * 12+3000 年薪 from emp</code>      <strong>使用引号添加别名,不能使用单引号</strong></li>
<li><code>select ename as 姓名,job &quot;工作&quot;,sal * 12 年资,sal * 12+3000 年薪 from emp</code>      <strong>使用as关键字添加别名</strong></li>
<li><code>select ename &quot;姓  名&quot;,job 工作,sal * 12 年资,sal * 12+3000 年薪 from emp</code>      <strong>如果别名中有空格或者其他特殊字符，使用双引号</strong></li>
</ul>
</li>
<li>推荐<ul>
<li>推荐使用别名操作时as不省略，别名加上双引号，方便维护操作<br> <strong><code>select ename as &quot;姓名&quot; from emp;</code></strong></li>
</ul>
</li>
</ul>
<h2 id="链接符操作"><a href="#链接符操作" class="headerlink" title="链接符操作-||"></a>链接符操作-||</h2><ul>
<li>介绍<ul>
<li>链接符就是将两个字符或者字符串链接，在java中链接符为“+”，而在sql中链接符为“||”。</li>
</ul>
</li>
<li>实例<ul>
<li><code>select ename||job,sal from emp;</code>  使用||符号进行字符链接<br><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200405125550.png" alt=""></li>
<li><code>select ename||&#39;  的工作是  &#39;||job||&#39;  并且月工资是  &#39;||sal from emp;</code>  字符链接，<strong>普通字符使用单引号</strong><br><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200405125552.png" alt=""></li>
</ul>
</li>
<li>技巧<ul>
<li>由于两个字段名使用链接符操作之后，字段名称也会相应改变。所以我们可以是用as给新生成的字段名起个别名</li>
<li><code>select ename||&#39;  的工作是  &#39;||job||&#39;  并且月工资是  &#39;||sal as &quot;信息&quot; from emp;</code><br><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200405125605.png" alt=""></li>
</ul>
</li>
</ul>
<h2 id="去重操作-distinct"><a href="#去重操作-distinct" class="headerlink" title="去重操作-distinct"></a>去重操作-distinct</h2><ul>
<li>介绍<ul>
<li>使用distinct关键字进行去重操作</li>
</ul>
</li>
<li>实例<ul>
<li>查看员工工作种类：<code>select distinct job from emp</code>  使用distinct关键字去除重复<br>值</li>
<li>多字段去除重复：<code>select distinct job,sal from emp;</code>  <strong>多字段去除重复，去除的是重复的完全相同一整条信息</strong>                    </li>
</ul>
</li>
</ul>
<h2 id="排序操作-order-by"><a href="#排序操作-order-by" class="headerlink" title="排序操作-order by"></a>排序操作-order by</h2><ul>
<li>知识点<ul>
<li>select *from 表名 order by 字段名</li>
<li>select 字段名，字段名…from 表名 order by 字段名</li>
</ul>
</li>
<li>实例<ul>
<li>查询按照薪资排序的员工姓名，工作，薪资<ul>
<li><code>select ename,job,sal from emp order by sal;</code>（默认升序）</li>
<li><code>select ename,job,sal from emp order by sal desc;</code> （降序）</li>
<li><code>select ename,job,sal from emp order by sal asc</code>（升序）</li>
</ul>
</li>
<li>查询多条件排序<ul>
<li><code>select * from emp order by sal,ename</code> <strong>多字段作为排序条件的时候，优先按照第一个字段排序，然后依次按照其他字段排序。</strong></li>
</ul>
</li>
<li>逻辑运算<ul>
<li><code>select ename,job,sal * 10 from emp order by sal;</code>（按照工资x10升序排序）</li>
</ul>
</li>
<li>别名使用<ul>
<li><code>select ename,job,sal as &quot;工资&quot; from emp order by &quot;工资&quot;;</code></li>
</ul>
</li>
</ul>
</li>
</ul>
<h2 id="简单的where子句"><a href="#简单的where子句" class="headerlink" title="简单的where子句"></a>简单的where子句</h2><ul>
<li>使用<ul>
<li>语法：<code>select * from 表名 where 条件；</code><strong>条件中字段值区分大小写，字段名不区分大小写，字段值使用单引号括起来</strong><ul>
<li>注意：<ul>
<li>1、在where中使用算术表达式 = ,&lt; , &gt; ,&gt;= ,&lt;= ,<strong>&lt;&gt;（不等于）</strong></li>
<li><strong>2、使用order by 对筛选结果进行排序，order by 出现在where后面</strong></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li>实例<ul>
<li>查看工资等于1250的员工信息<br> <strong><code>select * from emp where sal=&#39;1250&#39;</code>–筛选条件是个数字也可以使用单引号</strong></li>
<li>查看工作等于CLERK的员工信息<br> <strong><code>select * from emp where job=&#39;CLERK&#39;</code>–在筛选条件中字段值如果是字符需要加上单引号</strong><br> <code>select * from emp where job=&#39;clerk&#39;</code>–在sql语句中字段的值是区分大小写的<br> <code>select * from emp where JOB=&#39;CLERK&#39;</code>–在sql中字段是不区分大小写的</li>
<li>查看工资大于1250的员工姓名和工作<br> <strong><code>select ename,job ,sal from emp   where sal&gt;&#39;1250&#39; order by sal</code>–使用order by 对筛选结果进行排序，order by 出现在where后面</strong></li>
<li>查看工资大于等于2000的员工信息<br> <code>select * from emp where sal&gt;=2000;</code></li>
<li>查看工资小于等于2000的员工信息；<br> <code>select * from emp where sal&lt;=2000</code></li>
<li>查看工资不等于1500的员工信息<br> <strong><code>select * from emp where sal&lt;&gt;1500 order by sal</code></strong></li>
<li>查看入职日期在81年后的员工信息<br> <code>select * from emp where hiredate&gt;&#39;1981年12月31号&#39;</code><br> <code>select * from emp where hiredate&gt;&#39;1981/12/31&#39;</code><br> <strong><code>select * from emp where hiredate&gt;&#39;31-12月-1981&#39;</code>–使用日期的默认格式查询符合要求的数据，日-月-年</strong></li>
<li><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200405125451.png" alt="image-20200211171201957"></li>
</ul>
</li>
</ul>
<h2 id="where子句使用关键字"><a href="#where子句使用关键字" class="headerlink" title="where子句使用关键字"></a>where子句使用关键字</h2><ul>
<li>知识点 <ul>
<li>and 用于多条件的与筛选：<code>select * from 表名 where 条件 and 条件 and ....</code></li>
<li>or 用于多条件的或筛选： <code>select * from 表名 where 条件 or 条件 or 条件....</code></li>
<li>in 用于多条件的或筛选： <code>select * from 表名 where 字段名 in(值，值，值....)</code></li>
<li>like用于模糊查询：      <code>select * from 表名 where 字段名 like &#39;%值%&#39; 包含</code></li>
<li>is null 和is not null 用来判断字段是否为空  <code>select * from 表名　where 字段名 is null</code></li>
</ul>
</li>
<li>实例<ul>
<li>查询工资在2000-3000之间的员工信息<br> <code>select * from emp where sal&gt;=2000 and sal&lt;=3000</code>–使用and关键字进行”与”的多条件筛选；<br> <code>select * from emp where sal between 2000 and 3000;</code>–使用between and 关键字进行筛选；</li>
<li>查询工作为SALESMAN,ANALYST,MANAGER的员工信息<br> <code>select  * from emp where job=&#39;SALESMAN&#39; or job=&#39;ANALYST&#39; or job=&#39;MANAGER&#39;</code>–使用or关键字进行”或”的多条件筛选<br> <strong><code>select * from emp where job in(&#39;SALESMAN&#39;,&#39;ANALYST&#39;,&#39;MANAGER&#39;);</code>–使用in关键字进行”或”的多条件筛选</strong><br> <code>select  * from emp where job=&#39;ANALYST&#39;</code></li>
<li>查询姓名中包含s的，以s开头的，以s结尾的，第二个字符为A的。<br> <strong><code>select * from emp where ename like &#39;%S%&#39;;</code>–使用like关键字，姓名中包含S的,%代表任意多个字符</strong><br> <strong><code>select * from emp where ename like &#39;S%&#39;;</code>–使用like关键字，以S开头的</strong><br> <strong><code>select * from emp where ename like &#39;%S&#39;;</code>–以S结尾的</strong><br> <strong><code>select * from emp where ename like &#39;_A%&#39;</code>–使用”<em>“指定位置包含指定字符的信息，”</em>“代表任意一个字符</strong></li>
<li>查询名字中包含下划线的用户信息<br> <strong><code>select * from emp where ename like &#39;%A_%&#39;escape &#39;A&#39;;</code>–使用escape关键字将普通字符设置成为转译字符。</strong></li>
<li>查询有津贴的员工信息<br> <strong><code>select * from emp where comm is not null;</code></strong><br> <strong><code>select * from emp where comm is null;</code>–查询没有津贴的员工信息</strong></li>
</ul>
</li>
</ul>
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class="toc-text">Oracle创建用户</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Oracle%E4%BF%AE%E6%94%B9%E5%AF%86%E7%A0%81"><span class="toc-number">4.</span> <span class="toc-text">Oracle修改密码</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%8D%95%E8%A1%A8%E6%9F%A5%E8%AF%A2-select"><span class="toc-number">5.</span> <span class="toc-text">单表查询-select</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%88%AB%E5%90%8D%E6%93%8D%E4%BD%9C-as"><span class="toc-number">6.</span> <span class="toc-text">别名操作-as</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E9%93%BE%E6%8E%A5%E7%AC%A6%E6%93%8D%E4%BD%9C"><span class="toc-number">7.</span> <span class="toc-text">链接符操作-||</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%8E%BB%E9%87%8D%E6%93%8D%E4%BD%9C-distinct"><span class="toc-number">8.</span> <span class="toc-text">去重操作-distinct</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E6%8E%92%E5%BA%8F%E6%93%8D%E4%BD%9C-order-by"><span class="toc-number">9.</span> <span class="toc-text">排序操作-order by</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E7%AE%80%E5%8D%95%E7%9A%84where%E5%AD%90%E5%8F%A5"><span class="toc-number">10.</span> <span class="toc-text">简单的where子句</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#where%E5%AD%90%E5%8F%A5%E4%BD%BF%E7%94%A8%E5%85%B3%E9%94%AE%E5%AD%97"><span class="toc-number">11.</span> <span class="toc-text">where子句使用关键字</span></a></li></ol></div></div><div class="card-widget card-recent-post"><div class="item-headline"><i class="fas fa-history"></i><span>最新文章</span></div><div class="aside-list"><div class="aside-list-item"><a class="thumbnail" href="/56352.html" title="be动词"><img data-lazy-src="https://qiniu.codekylin.cn/github/img/img/博客封面10.png" onerror="this.onerror=null;this.src='/img/404.jpg'" alt="be动词"/></a><div 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